A 7.6-magnitude quake struck off the eastern coast of the Philippines today, killing at least one person in a house collapse, knocking out power in several towns and generating negligible tsunami surges.

A tsunami alert originally was issued for several countries in the region including Indonesia and Japan and for Pacific islands as far away as the Northern Marianas, but they all were later lifted, the Pacific Tsunami Warning Centre said.

The centre said that very small tsunami waves of just over an inch were recorded along the eastern Philippine coast near Legazpi city and another nearby location.

Benito Ramos, a retired general who heads the country's disaster-response agency, said in an advisory broadcast nationwide that residents should be on the alert for aftershocks.

"Don't sleep, especially those in the eastern seaboard ... because there might be aftershocks," he said.

Initial warnings of a possible substantial tsunami prompted many coastal residents in the Philippines to head for high ground.

The quake, with preliminary magnitude 7.6, hit at a depth of 21.7 miles and was centred 66 miles east of Samar Island, the US Geological Survey said.

One house collapsed in southern Cagayan de Oro city, on the main southern island of Mindanao, killing a 54-year-old woman and injuring her five-year-old grandson, who was being treated in a hospital, said the city's mayor, Vicente Emano.

The quake knocked out power in several other towns and cities across the central and southern Philippines, though it was restored in some areas later Friday, according to rescuers and local radio reports.